pjs/xpcom/ds/nsBuffer.cpp

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* The contents of this file are subject to the Netscape Public License
* Version 1.0 (the "NPL"); you may not use this file except in
* compliance with the NPL. You may obtain a copy of the NPL at
* http://www.mozilla.org/NPL/
*
* Software distributed under the NPL is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
* for the specific language governing rights and limitations under the
* NPL.
*
* The Initial Developer of this code under the NPL is Netscape
* Communications Corporation. Portions created by Netscape are
* Copyright (C) 1998 Netscape Communications Corporation. All Rights
* Reserved.
*/
#include "nsBuffer.h"
#include "nsAutoLock.h"
#include "nsCRT.h"
#include "nsIInputStream.h"
#include "nsIServiceManager.h"
#include "nsIPageManager.h"
////////////////////////////////////////////////////////////////////////////////
nsBuffer::nsBuffer()
: mGrowBySize(0),
mMaxSize(0),
mAllocator(nsnull),
mBufferSize(0),
mReadSegment(nsnull),
mReadCursor(0),
mWriteSegment(nsnull),
mWriteCursor(0),
mReaderClosed(PR_FALSE),
mCondition(NS_OK)
{
NS_INIT_REFCNT();
PR_INIT_CLIST(&mSegments);
}
NS_IMETHODIMP
nsBuffer::Init(PRUint32 growBySize, PRUint32 maxSize,
nsIBufferObserver* observer, nsIAllocator* allocator)
{
NS_ASSERTION(sizeof(PRCList) <= SEGMENT_OVERHEAD,
"need to change SEGMENT_OVERHEAD size");
NS_ASSERTION(growBySize > SEGMENT_OVERHEAD, "bad growBySize");
mGrowBySize = growBySize;
mMaxSize = maxSize;
mObserver = observer;
NS_IF_ADDREF(mObserver);
mAllocator = allocator;
NS_ADDREF(mAllocator);
return NS_OK;
}
nsBuffer::~nsBuffer()
{
NS_IF_RELEASE(mObserver);
NS_IF_RELEASE(mAllocator);
}
NS_IMPL_ISUPPORTS(nsBuffer, nsIBuffer::GetIID());
NS_METHOD
nsBuffer::Create(nsISupports *aOuter, REFNSIID aIID, void **aResult)
{
if (aOuter)
return NS_ERROR_NO_AGGREGATION;
nsBuffer* buf = new nsBuffer();
if (buf == nsnull)
return NS_ERROR_OUT_OF_MEMORY;
NS_ADDREF(buf);
nsresult rv = buf->QueryInterface(aIID, aResult);
NS_RELEASE(buf);
return rv;
}
////////////////////////////////////////////////////////////////////////////////
nsresult
nsBuffer::PushWriteSegment()
{
nsAutoCMonitor mon(this); // protect mSegments
if (mBufferSize >= mMaxSize) {
if (mObserver) {
nsresult rv = mObserver->OnFull(this);
if (NS_FAILED(rv)) return rv;
}
return NS_BASE_STREAM_WOULD_BLOCK;
}
// allocate a new segment to write into
PRCList* header;
header = (PRCList*)mAllocator->Alloc(mGrowBySize);
if (header == nsnull)
return NS_ERROR_OUT_OF_MEMORY;
mBufferSize += mGrowBySize;
PR_INSERT_BEFORE(header, &mSegments); // insert at end
// initialize the write segment
mWriteSegment = header;
mWriteSegmentEnd = (char*)mWriteSegment + mGrowBySize;
mWriteCursor = (char*)mWriteSegment + sizeof(PRCList);
return NS_OK;
}
nsresult
nsBuffer::PopReadSegment()
{
nsresult rv;
nsAutoCMonitor mon(this); // protect mSegments
PRCList* header = (PRCList*)mSegments.next;
char* segment = (char*)header;
NS_ASSERTION(mReadSegment == header, "wrong segment");
// make sure that the writer isn't still in this segment (that the
// reader is removing)
NS_ASSERTION(!(segment <= mWriteCursor && mWriteCursor < segment + mGrowBySize),
"removing writer's segment");
PR_REMOVE_LINK(header); // unlink from mSegments
mBufferSize -= mGrowBySize;
rv = mAllocator->Free(segment);
if (NS_FAILED(rv)) return rv;
// initialize the read segment
if (PR_CLIST_IS_EMPTY(&mSegments)) {
mReadSegment = nsnull;
mReadSegmentEnd = nsnull;
mReadCursor = nsnull;
if (mObserver) {
rv = mObserver->OnEmpty(this);
if (NS_FAILED(rv)) return rv;
}
return NS_BASE_STREAM_WOULD_BLOCK;
}
else {
mReadSegment = mSegments.next;
mReadSegmentEnd = (char*)mReadSegment + mGrowBySize;
mReadCursor = (char*)mReadSegment + sizeof(PRCList);
}
return NS_OK;
}
////////////////////////////////////////////////////////////////////////////////
// nsIBuffer methods:
NS_IMETHODIMP
nsBuffer::ReadSegments(nsWriteSegmentFun writer, void* closure, PRUint32 count,
PRUint32 *readCount)
{
NS_ASSERTION(!mReaderClosed, "state change error");
nsAutoCMonitor mon(this);
nsresult rv = NS_OK;
PRUint32 readBufferLen;
const char* readBuffer;
*readCount = 0;
while (count > 0) {
rv = GetReadSegment(0, &readBuffer, &readBufferLen);
if (NS_FAILED(rv) || readBufferLen == 0) {
return *readCount == 0 ? rv : NS_OK;
}
readBufferLen = PR_MIN(readBufferLen, count);
while (readBufferLen > 0) {
PRUint32 writeCount;
rv = writer(closure, readBuffer, *readCount, readBufferLen, &writeCount);
NS_ASSERTION(rv != NS_BASE_STREAM_EOF, "Write should not return EOF");
if (rv == NS_BASE_STREAM_WOULD_BLOCK || NS_FAILED(rv) || writeCount == 0) {
// if we failed to write just report what we were
// able to read so far
return *readCount == 0 ? rv : NS_OK;
}
NS_ASSERTION(writeCount <= readBufferLen, "writer returned bad writeCount");
readBuffer += writeCount;
readBufferLen -= writeCount;
*readCount += writeCount;
count -= writeCount;
if (mReadCursor + writeCount == mReadSegmentEnd) {
rv = PopReadSegment();
if (NS_FAILED(rv)) {
return *readCount == 0 ? rv : NS_OK;
}
}
else {
mReadCursor += writeCount;
}
}
}
return NS_OK;
}
static NS_METHOD
nsWriteToRawBuffer(void* closure,
const char* fromRawSegment,
PRUint32 offset,
PRUint32 count,
PRUint32 *writeCount)
{
char* toBuf = (char*)closure;
nsCRT::memcpy(&toBuf[offset], fromRawSegment, count);
*writeCount = count;
return NS_OK;
}
NS_IMETHODIMP
nsBuffer::Read(char* toBuf, PRUint32 bufLen, PRUint32 *readCount)
{
return ReadSegments(nsWriteToRawBuffer, toBuf, bufLen, readCount);
}
NS_IMETHODIMP
nsBuffer::GetReadSegment(PRUint32 segmentLogicalOffset,
const char* *resultSegment,
PRUint32 *resultSegmentLen)
{
nsAutoCMonitor mon(this);
// set the read segment and cursor if not already set
if (mReadSegment == nsnull) {
if (PR_CLIST_IS_EMPTY(&mSegments)) {
*resultSegmentLen = 0;
*resultSegment = nsnull;
return mCondition;
}
else {
mReadSegment = mSegments.next;
mReadSegmentEnd = (char*)mReadSegment + mGrowBySize;
mReadCursor = (char*)mReadSegment + sizeof(PRCList);
}
}
// now search for the segment starting from segmentLogicalOffset and return it
PRCList* curSeg = mReadSegment;
char* curSegStart = mReadCursor;
char* curSegEnd = mReadSegmentEnd;
PRInt32 amt;
PRInt32 offset = (PRInt32)segmentLogicalOffset;
while (offset >= 0) {
// snapshot the write cursor into a local variable -- this allows
// a writer to freely change it while we're reading while avoiding
// using a lock
char* snapshotWriteCursor = mWriteCursor; // atomic
// next check if the write cursor is in our segment
if (curSegStart <= snapshotWriteCursor &&
snapshotWriteCursor < curSegEnd) {
// same segment -- read up to the snapshotWriteCursor
curSegEnd = snapshotWriteCursor;
amt = curSegEnd - curSegStart;
if (offset < amt) {
// segmentLogicalOffset is in this segment, so read up to its end
*resultSegmentLen = amt - offset;
*resultSegment = curSegStart + offset;
return NS_OK;
}
else {
// don't continue past the write segment
*resultSegmentLen = 0;
*resultSegment = nsnull;
return mCondition;
}
}
else {
amt = curSegEnd - curSegStart;
if (offset < amt) {
// segmentLogicalOffset is in this segment, so read up to its end
*resultSegmentLen = amt - offset;
*resultSegment = curSegStart + offset;
return NS_OK;
}
else {
curSeg = PR_NEXT_LINK(curSeg);
if (curSeg == mReadSegment) {
// been all the way around
*resultSegmentLen = 0;
*resultSegment = nsnull;
return mCondition;
}
curSegEnd = (char*)curSeg + mGrowBySize;
curSegStart = (char*)curSeg + sizeof(PRCList);
offset -= amt;
}
}
}
NS_NOTREACHED("nsBuffer::GetReadSegment failed");
return NS_ERROR_FAILURE;
}
NS_IMETHODIMP
nsBuffer::GetReadableAmount(PRUint32 *result)
{
NS_ASSERTION(!mReaderClosed, "state change error");
nsAutoCMonitor mon(this);
*result = 0;
// first set the read segment and cursor if not already set
if (mReadSegment == nsnull) {
if (PR_CLIST_IS_EMPTY(&mSegments)) {
return NS_OK;
}
else {
mReadSegment = mSegments.next;
mReadSegmentEnd = (char*)mReadSegment + mGrowBySize;
mReadCursor = (char*)mReadSegment + sizeof(PRCList);
}
}
// now search for the segment starting from segmentLogicalOffset and return it
PRCList* curSeg = mReadSegment;
char* curSegStart = mReadCursor;
char* curSegEnd = mReadSegmentEnd;
PRInt32 amt;
while (PR_TRUE) {
// snapshot the write cursor into a local variable -- this allows
// a writer to freely change it while we're reading while avoiding
// using a lock
char* snapshotWriteCursor = mWriteCursor; // atomic
// next check if the write cursor is in our segment
if (curSegStart <= snapshotWriteCursor &&
snapshotWriteCursor < curSegEnd) {
// same segment -- read up to the snapshotWriteCursor
curSegEnd = snapshotWriteCursor;
amt = curSegEnd - curSegStart;
*result += amt;
return NS_OK;
}
else {
amt = curSegEnd - curSegStart;
*result += amt;
curSeg = PR_NEXT_LINK(curSeg);
if (curSeg == mReadSegment) {
// been all the way around
return NS_OK;
}
curSegEnd = (char*)curSeg + mGrowBySize;
curSegStart = (char*)curSeg + sizeof(PRCList);
}
}
return NS_ERROR_FAILURE;
}
#define COMPARE(s1, s2, i) ignoreCase ? nsCRT::strncasecmp((const char *)s1, (const char *)s2, (PRUint32)i) : nsCRT::strncmp((const char *)s1, (const char *)s2, (PRUint32)i)
NS_IMETHODIMP
nsBuffer::Search(const char* string, PRBool ignoreCase,
PRBool *found, PRUint32 *offsetSearchedTo)
{
NS_ASSERTION(!mReaderClosed, "state change error");
nsresult rv;
const char* bufSeg1;
PRUint32 bufSegLen1;
PRUint32 segmentPos = 0;
PRUint32 strLen = nsCRT::strlen(string);
rv = GetReadSegment(segmentPos, &bufSeg1, &bufSegLen1);
if (NS_FAILED(rv) || bufSegLen1 == 0) {
*found = PR_FALSE;
*offsetSearchedTo = segmentPos;
return NS_OK;
}
while (PR_TRUE) {
PRUint32 i;
// check if the string is in the buffer segment
for (i = 0; i < bufSegLen1 - strLen + 1; i++) {
if (COMPARE(&bufSeg1[i], string, strLen) == 0) {
*found = PR_TRUE;
*offsetSearchedTo = segmentPos + i;
return NS_OK;
}
}
// get the next segment
const char* bufSeg2;
PRUint32 bufSegLen2;
segmentPos += bufSegLen1;
rv = GetReadSegment(segmentPos, &bufSeg2, &bufSegLen2);
if (NS_FAILED(rv) || bufSegLen2 == 0) {
*found = PR_FALSE;
if (mCondition != NS_OK) // XXX NS_FAILED?
*offsetSearchedTo = segmentPos - bufSegLen1;
else
*offsetSearchedTo = segmentPos - bufSegLen1 - strLen + 1;
return NS_OK;
}
// check if the string is straddling the next buffer segment
PRUint32 limit = PR_MIN(strLen, bufSegLen2 + 1);
for (i = 0; i < limit; i++) {
PRUint32 strPart1Len = strLen - i - 1;
PRUint32 strPart2Len = strLen - strPart1Len;
const char* strPart2 = &string[strLen - strPart2Len];
PRUint32 bufSeg1Offset = bufSegLen1 - strPart1Len;
if (COMPARE(&bufSeg1[bufSeg1Offset], string, strPart1Len) == 0 &&
COMPARE(bufSeg2, strPart2, strPart2Len) == 0) {
*found = PR_TRUE;
*offsetSearchedTo = segmentPos - strPart1Len;
return NS_OK;
}
}
// finally continue with the next buffer
bufSeg1 = bufSeg2;
bufSegLen1 = bufSegLen2;
}
NS_NOTREACHED("can't get here");
return NS_ERROR_FAILURE; // keep compiler happy
}
NS_IMETHODIMP
nsBuffer::ReaderClosed()
{
nsresult rv = NS_OK;
nsAutoCMonitor mon(this); // protect mSegments
// first prevent any more writing
mReaderClosed = PR_TRUE;
// then free any unread segments...
// first set the read segment and cursor if not already set
if (mReadSegment == nsnull) {
if (!PR_CLIST_IS_EMPTY(&mSegments)) {
mReadSegment = mSegments.next;
mReadSegmentEnd = (char*)mReadSegment + mGrowBySize;
mReadCursor = (char*)mReadSegment + sizeof(PRCList);
}
}
while (mReadSegment) {
// snapshot the write cursor into a local variable -- this allows
// a writer to freely change it while we're reading while avoiding
// using a lock
char* snapshotWriteCursor = mWriteCursor; // atomic
// next check if the write cursor is in our segment
if (mReadCursor <= snapshotWriteCursor &&
snapshotWriteCursor < mReadSegmentEnd) {
// same segment -- we've discarded all the unread segments we
// can, so just updatethe read cursor
mReadCursor = mWriteCursor;
break;
}
// else advance to the next segment, freeing this one
rv = PopReadSegment();
if (NS_FAILED(rv)) break;
}
#ifdef DEBUG
PRUint32 amt;
const char* buf;
rv = GetReadSegment(0, &buf, &amt);
NS_ASSERTION(rv == NS_BASE_STREAM_EOF ||
(NS_SUCCEEDED(rv) && amt == 0), "ReaderClosed failed");
#endif
return rv;
}
NS_IMETHODIMP
nsBuffer::GetCondition(nsresult *result)
{
*result = mCondition;
return NS_OK;
}
////////////////////////////////////////////////////////////////////////////////
NS_IMETHODIMP
nsBuffer::WriteSegments(nsReadSegmentFun reader, void* closure, PRUint32 count,
PRUint32 *writeCount)
{
nsresult rv = NS_OK;
PR_CEnterMonitor(this);
*writeCount = 0;
if (mReaderClosed) {
rv = NS_BASE_STREAM_CLOSED;
goto done;
}
if (NS_FAILED(mCondition)) {
rv = mCondition;
goto done;
}
while (count > 0) {
PRUint32 writeBufLen;
char* writeBuf;
rv = GetWriteSegment(&writeBuf, &writeBufLen);
if (NS_FAILED(rv) || writeBufLen == 0) {
// if we failed to allocate a new segment, we're probably out
// of memory, but we don't care -- just report what we were
// able to write so far
rv = (*writeCount == 0) ? rv : NS_OK;
goto done;
}
writeBufLen = PR_MIN(writeBufLen, count);
while (writeBufLen > 0) {
PRUint32 readCount;
rv = reader(closure, writeBuf, *writeCount, writeBufLen, &readCount);
if (rv == NS_BASE_STREAM_WOULD_BLOCK || readCount == 0) {
// if the place we're putting the data would block (probably ran
// out of room) just return what we were able to write so far
rv = (*writeCount == 0) ? rv : NS_OK;
goto done;
}
if (NS_FAILED(rv)) {
// save the failure condition so that we can get it again later
nsresult rv2 = SetCondition(rv);
NS_ASSERTION(NS_SUCCEEDED(rv2), "SetCondition failed");
// if we failed to read just report what we were
// able to write so far
rv = (*writeCount == 0) ? rv : NS_OK;
goto done;
}
NS_ASSERTION(readCount <= writeBufLen, "reader returned bad readCount");
writeBuf += readCount;
writeBufLen -= readCount;
*writeCount += readCount;
count -= readCount;
// set the write cursor after the data is valid
if (mWriteCursor + readCount == mWriteSegmentEnd) {
mWriteSegment = nsnull; // allocate a new segment next time around
mWriteSegmentEnd = nsnull;
mWriteCursor = nsnull;
}
else
mWriteCursor += readCount;
}
}
done:
PR_CExitMonitor(this);
if (mObserver && *writeCount) {
mObserver->OnWrite(this, *writeCount);
}
return rv;
}
static NS_METHOD
nsReadFromRawBuffer(void* closure,
char* toRawSegment,
PRUint32 offset,
PRUint32 count,
PRUint32 *readCount)
{
const char* fromBuf = (const char*)closure;
nsCRT::memcpy(toRawSegment, &fromBuf[offset], count);
*readCount = count;
return NS_OK;
}
NS_IMETHODIMP
nsBuffer::Write(const char* fromBuf, PRUint32 bufLen, PRUint32 *writeCount)
{
return WriteSegments(nsReadFromRawBuffer, (void*)fromBuf, bufLen, writeCount);
}
static NS_METHOD
nsReadFromInputStream(void* closure,
char* toRawSegment,
PRUint32 offset,
PRUint32 count,
PRUint32 *readCount)
{
nsIInputStream* fromStream = (nsIInputStream*)closure;
return fromStream->Read(toRawSegment, count, readCount);
}
NS_IMETHODIMP
nsBuffer::WriteFrom(nsIInputStream* fromStream, PRUint32 count, PRUint32 *writeCount)
{
return WriteSegments(nsReadFromInputStream, fromStream, count, writeCount);
}
NS_IMETHODIMP
nsBuffer::GetWriteSegment(char* *resultSegment,
PRUint32 *resultSegmentLen)
{
nsAutoCMonitor mon(this);
if (mReaderClosed)
return NS_BASE_STREAM_CLOSED;
nsresult rv;
*resultSegmentLen = 0;
*resultSegment = nsnull;
if (mWriteSegment == nsnull) {
rv = PushWriteSegment();
if (NS_FAILED(rv) || rv == NS_BASE_STREAM_WOULD_BLOCK) return rv;
NS_ASSERTION(mWriteSegment != nsnull, "failed to allocate segment");
}
*resultSegmentLen = mWriteSegmentEnd - mWriteCursor;
*resultSegment = mWriteCursor;
NS_ASSERTION(*resultSegmentLen > 0, "Failed to get write segment.");
return NS_OK;
}
NS_IMETHODIMP
nsBuffer::GetWritableAmount(PRUint32 *amount)
{
if (mReaderClosed)
return NS_BASE_STREAM_CLOSED;
nsresult rv;
PRUint32 readableAmount;
rv = GetReadableAmount(&readableAmount);
if (NS_FAILED(rv)) return rv;
*amount = mMaxSize - readableAmount;
return NS_OK;
}
NS_IMETHODIMP
nsBuffer::GetReaderClosed(PRBool *result)
{
*result = mReaderClosed;
return NS_OK;
}
NS_IMETHODIMP
nsBuffer::SetCondition(nsresult condition)
{
nsAutoCMonitor mon(this);
if (mReaderClosed)
return NS_BASE_STREAM_CLOSED;
mCondition = condition;
mWriteSegment = nsnull; // allows reader to free last segment w/o asserting
mWriteSegmentEnd = nsnull;
// don't reset mWriteCursor here -- we need it for the EOF point in the buffer
return NS_OK;
}
////////////////////////////////////////////////////////////////////////////////
static NS_DEFINE_CID(kAllocatorCID, NS_ALLOCATOR_CID);
NS_COM nsresult
NS_NewBuffer(nsIBuffer* *result,
PRUint32 growBySize, PRUint32 maxSize,
nsIBufferObserver* observer)
{
nsresult rv;
NS_WITH_SERVICE(nsIAllocator, alloc, kAllocatorCID, &rv);
if (NS_FAILED(rv)) return rv;
nsBuffer* buf;
rv = nsBuffer::Create(NULL, nsIBuffer::GetIID(), (void**)&buf);
if (NS_FAILED(rv)) return rv;
rv = buf->Init(growBySize, maxSize, observer, alloc);
if (NS_FAILED(rv)) {
NS_RELEASE(buf);
return rv;
}
*result = buf;
return NS_OK;
}
static NS_DEFINE_CID(kPageManagerCID, NS_PAGEMANAGER_CID);
NS_COM nsresult
NS_NewPageBuffer(nsIBuffer* *result,
PRUint32 growBySize, PRUint32 maxSize,
nsIBufferObserver* observer)
{
nsresult rv;
NS_WITH_SERVICE(nsIAllocator, alloc, kPageManagerCID, &rv);
if (NS_FAILED(rv)) return rv;
nsBuffer* buf;
rv = nsBuffer::Create(NULL, nsIBuffer::GetIID(), (void**)&buf);
if (NS_FAILED(rv)) return rv;
rv = buf->Init(growBySize, maxSize, observer, alloc);
if (NS_FAILED(rv)) {
NS_RELEASE(buf);
return rv;
}
*result = buf;
return NS_OK;
}
////////////////////////////////////////////////////////////////////////////////